A high nuclear basal level of ERK2 phosphorylation contributes to the resistance of cisplatin-resistant human ovarian cancer cells

Gynecol Oncol. 2007 Feb;104(2):338-44. doi: 10.1016/j.ygyno.2006.08.040. Epub 2006 Oct 4.

Abstract

Objective: The aim of this study was to elucidate the role of ERK1/2 on cisplatin resistance in human ovarian cancer cells.

Methods: The relationship between nuclear levels of ERK2 and cisplatin-induced apoptosis in human ovarian carcinoma cell line, OVCAR-3, and in cells of the cisplatin-resistant subclone, OVCAR-3/CDDP, was examined using immunoblotting and immunocytochemistry.

Results: Cisplatin treatment resulted in the activation of ERK2, both in OVCAR-3 and OVCAR-3/CDDP cells. However, considerable levels of activated ERK2 existed in the nuclei of OVCAR-3/CDDP cells during serum starvation and in the early period (1-3 h) after cisplatin treatment. Conversely, phospho-ERK2 was marginally detected in the nuclei of OVCAR-3 cells prior to cisplatin treatment. These phenomena were confirmed by immunofluorescence staining of the phosphorylated ERK2 in the nuclei of both cells. High basal phospho-ERK2 in the nuclei of OVCAR-3/CDDP cells contributed to cisplatin resistance, and was supported by several observations; (1) treatment of U0126, an inhibitor of MEK/ERK signaling pathway, partially sensitized OVCAR-3/CDDP cells to cisplatin; (2) pretreatment of OVCAR-3 cells with phorbol 12-myristate 13-acetate (PMA), an activator of ERK, induced nuclear translocation of activated ERK2, which led to the suppression of cisplatin-induced apoptosis.

Conclusions: These results collectively indicate that prelocalization of activated ERK2 in the nuclei contribute to cisplatin resistance in OVCAR-3/CDDP cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects
  • Apoptosis / physiology
  • Butadienes / pharmacology
  • Caspase 3 / metabolism
  • Cell Line, Tumor
  • Cell Nucleus / enzymology
  • Cisplatin / pharmacology*
  • Drug Resistance, Neoplasm
  • Drug Synergism
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • Female
  • Humans
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Nitriles / pharmacology
  • Ovarian Neoplasms / drug therapy*
  • Ovarian Neoplasms / enzymology*
  • Ovarian Neoplasms / pathology
  • Phosphorylation
  • Tetradecanoylphorbol Acetate / pharmacology

Substances

  • Antineoplastic Agents
  • Butadienes
  • Enzyme Inhibitors
  • Nitriles
  • U 0126
  • Mitogen-Activated Protein Kinase 1
  • Caspase 3
  • Tetradecanoylphorbol Acetate
  • Cisplatin